Polymers containing long perfluoroalkyl groups pendant to the main chain are widely used as oil- and water repellent coatings on textiles and paper. Usually such polymers are prepared by polymerization of a perfluoroalkyl group containing monomers, for instance esters of acrylic, methacrylic- or fumaric acid with R.sub.f (CH.sub.2).sub.n OH as described in U.S. Pat. Nos. 3,068,187, 3,304,278, 4,150,225 or by polycondensation of perfluoroalkyl-substituted diols with diisocyanates, as described in U.S. Pat. Nos. 3,499,940, 3,720,639, 3,935,277, 4,046,944, and 4,098,742.
In each case fluoroalkyl groups containing macromers are the starting material for swelling the corresponding polymer. Due to the bulkiness of the perfluoroalkyl group and its high molecular weight it is difficult and in most structures impossible to reach the high degrees of polymerization necessary to get coatings or shaped articles of great toughness. In addition, the insolubility of highly fluorinated monomers in common organic solvents complicates the synthesis. For these reasons, the perfluoroalkyl substituted polymers reported in the literature are copolymers with non-fluorinated monomers; in this manner high molecular weight polymers can be prepared, but of a relatively low fluorine content.
It has now been discovered, that when perfluoroalkyl substituted thiols are added to a preformed, unsaturated polymer, highly fluorinated prepolymers are obtained which can be used to make tough, abrasive-resistant and oil/and water repellent coatings or articles.
More specifically, this invention described the synthesis of perfluoroalkyl-substiuted polymers by addition of perfluoroalkylalkylene thiols to polydienes, followed optionally by an oxidation of the resulting thioether product to the corresponding sulfoxide and/or sulfone. These polymers are useful as non-wettable, hard coatings for metal, glass, ceramics, masonary, wood, fibers, textiles plastics or other substrates or they can be fabricated into tough polyurethane rubbers, epoxies or polyesters.